The invention relates to a device for coupling a heddle frame with an oscillatory drive element comprising a pair of elements which are engageable one into the other and which, in use, are disposed one on the frame stave of the heddle frame and the other on the drive element, and a bolt latch which is pivotally mounted on one of the coupling elements so that it can be pressed against the other coupling element when the coupling elements are engaged, the bolt latch having wedge surfaces extending transversely to the direction of drive and arranged to co-operate with counter-surfaces on the other coupling element when the latch is pressed against it to produce a positive locking of the coupling elements in the engaged position.
There are numerous different coupling constructions for detachably connecting a heddle frame to the driving element which moves up and down, also called a drive bar. In these constructions the coupling elements are generally designed with a particular aim, such as to prevent too rapid a wear of the coupling parts, or to provide a very fast and simple engagement and disengagement, or to enable a whole series of heddle frames placed one behind the other to be coupled or uncoupled from the driving elements simultaneously.
In a known arrangement of the last mentioned type, a locking element, which is pivotally mounted on a coupling element and is provided with wedge surfaces for co-operation with counter-wedge surfaces on the other coupling element associated with the heddle frame, is actuated by means of a rotatably mounted adjusting cam which has a square hole for the insertion of an actuating rod which can be simultaneously passed through the cam in the coupling devices of a plurality of heddle frames disposed one behind the other, so that all the heddle frames can be simultaneously separated from the driving elements. In the engaged position the cam presses against a rubber insert rigidly mounted on the locking element, and is held in this position by the tension of the pushed in rubber insert.
In operation the coupling parts are subjected to considerable forces as a result of the oscillating movement, and hence the securing of the cam in the locking position solely on the basis of the elasticity of the rubber material is not reliably ensured, particularly when, as a result of constant use and wear on the wedge surfaces of the coupling parts, a certain amount of play arises between them. This play, which is no present in the new condition, develops gradually and cannot be eliminated by means of the cam. The play brings with it very undesirable effects, such as the creation of mating rust, increased wear from the impacts occurring as a result of play, and vibration of the heddle frame, etc. With all drive coupling arrangements on heddle frames it is a drawback if a play-free connection is not ensured between the coupling parts even as they wear gradually.